linux-kernel - Re: [PATCH] riscv: make ZONE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Zu2A1l_cX36sOVcB@infradead.org>
Date: Fri, 20 Sep 2024 07:04:06 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH] riscv: make ZONE_DMA32 optional

On Tue, Aug 27, 2024 at 02:36:11PM +0300, Vladimir Kondratiev wrote:
> It is not necessary any RISCV platform has ZONE_DMA32.

That is an odd statement.  The point of ZONE_DMA32 is to make sure
that drivers can always allocate 32-bit DMAable memory, and without
ZONE_DMA32 that is very hard to provide unless you always have an
IOMMU.

> Example - if platform has no DRAM in [0..4G] region,
> it will report failure like below each boot.

ZONE_DMA32 is supposed to contain the 32-bit dma addressable memory,
not 32-bit physical.

Take a look at the changes that just went into Linus' tree for that.